add RestartGamemode command

This allows gamemode to leave the context and then enter it again, which
re-applies all system optimizations. It is useful in cases where another
program (like TLP) may override gamemode's optimizations.

This is exposed to users by the -R or --restart flags to gamemoded.

Author: MithicSpirit

daemon/gamemode-context.c

@@ -857,6 +857,49 @@ int game_mode_context_query_status(GameModeContext *self, pid_t client, pid_t re
 	return ret;
 }
 
+int game_mode_context_restart(GameModeContext *self, pid_t client, pid_t requester)
+{
+	/* First check the requester settings */
+	{
+		char *executable = game_mode_context_find_exe(requester);
+		if (!executable) {
+			return -1;
+		}
+
+		/* Check our blacklist and whitelist */
+		if (!config_get_supervisor_whitelisted(self->config, executable)) {
+			LOG_MSG("Supervisor [%s] was rejected (not in whitelist)\n", executable);
+			free(executable);
+			return -2;
+		} else if (config_get_supervisor_blacklisted(self->config, executable)) {
+			LOG_MSG("Supervisor [%s] was rejected (in blacklist)\n", executable);
+			free(executable);
+			return -2;
+		}
+
+		free(executable);
+	}
+
+	/*
+	 * Check the current refcount on gamemode, this equates to whether gamemode is active or not,
+	 * see game_mode_context_register and game_mode_context_unregister
+	 */
+	if (!atomic_load_explicit(&self->refcount, memory_order_seq_cst)) {
+		return 1;
+	}
+
+	/* Requires locking. */
+	pthread_rwlock_rdlock(&self->rwlock);
+
+	game_mode_context_leave(self);
+	game_mode_context_enter(self);
+
+	/* Unlock here, potentially yielding */
+	pthread_rwlock_unlock(&self->rwlock);
+
+	return 0;
+}
+
 /**
  * Construct a new GameModeClient for the given process ID
  *

daemon/gamemode-dbus.c

@@ -133,6 +133,26 @@ static int method_query_status(sd_bus_message *m, void *userdata,
 	return sd_bus_reply_method_return(m, "i", status);
 }
 
+/**
+ * Handles the RestartGamemode D-BUS Method
+ */
+static int method_restart_gamemode(sd_bus_message *m, void *userdata,
+                               __attribute__((unused)) sd_bus_error *ret_error)
+{
+	int pid = 0;
+	GameModeContext *context = userdata;
+
+	int ret = sd_bus_message_read(m, "i", &pid);
+	if (ret < 0) {
+		LOG_ERROR("Failed to parse input parameters: %s\n", strerror(-ret));
+		return ret;
+	}
+
+	int status = game_mode_context_restart(context, (pid_t)pid, (pid_t)pid);
+
+	return sd_bus_reply_method_return(m, "i", status);
+}
+
 /**
  * Handles the RegisterGameByPID D-BUS Method
  */
@@ -402,6 +422,7 @@ static const sd_bus_vtable gamemode_vtable[] = {
 	SD_BUS_METHOD("RegisterGame", "i", "i", method_register_game, SD_BUS_VTABLE_UNPRIVILEGED),
 	SD_BUS_METHOD("UnregisterGame", "i", "i", method_unregister_game, SD_BUS_VTABLE_UNPRIVILEGED),
 	SD_BUS_METHOD("QueryStatus", "i", "i", method_query_status, SD_BUS_VTABLE_UNPRIVILEGED),
+	SD_BUS_METHOD("RestartGamemode", "i", "i", method_restart_gamemode, SD_BUS_VTABLE_UNPRIVILEGED),
 	SD_BUS_METHOD("RegisterGameByPID", "ii", "i", method_register_game_by_pid,
 	              SD_BUS_VTABLE_UNPRIVILEGED),
 	SD_BUS_METHOD("UnregisterGameByPID", "ii", "i", method_unregister_game_by_pid,

daemon/gamemode.h

@@ -155,6 +155,16 @@ int game_mode_context_unregister(GameModeContext *self, pid_t pid, pid_t request
  */
 int game_mode_context_query_status(GameModeContext *self, pid_t pid, pid_t requester);
 
+/**
+ * Restart gamemode if it is running
+ *
+ * @param pid Process ID for the remote client
+ * @returns 0 if gamemode was restarted
+ *          1 if gamemode was already deactivated
+ *          -2 if this request was rejected
+ */
+int game_mode_context_restart(GameModeContext *self, pid_t pid, pid_t requester);
+
 /**
  * Query the config of a gamemode context
  *

daemon/gamemoded.c

@@ -70,6 +70,7 @@ POSSIBILITY OF SUCH DAMAGE.
 	"                           When no PID given, requests gamemode and pauses\n"                 \
 	"  -s[PID], --status=[PID]  Query the status of gamemode for process\n"                        \
 	"                           When no PID given, queries the status globally\n"                  \
+	"  -R, --reset              If gamemode is currently running, stop it, then restart\n"         \
 	"  -d, --daemonize          Daemonize self after launch\n"                                     \
 	"  -l, --log-to-syslog      Log to syslog\n"                                                   \
 	"  -t, --test               Run tests\n"                                                       \
@@ -161,9 +162,10 @@ int main(int argc, char *argv[])
 		{ "daemonize", no_argument, 0, 'd' },     { "log-to-syslog", no_argument, 0, 'l' },
 		{ "request", optional_argument, 0, 'r' }, { "test", no_argument, 0, 't' },
 		{ "status", optional_argument, 0, 's' },  { "help", no_argument, 0, 'h' },
-		{ "version", no_argument, 0, 'v' },       { NULL, 0, NULL, 0 },
+		{ "version", no_argument, 0, 'v' },       { "reset", no_argument, 0, 'R' },
+		{ NULL, 0, NULL, 0 },
 	};
-	static const char *short_options = "dls::r::tvh";
+	static const char *short_options = "dls::r::tvhR";
 
 	while ((opt = getopt_long(argc, argv, short_options, long_options, 0)) != -1) {
 		switch (opt) {
@@ -289,6 +291,20 @@ int main(int argc, char *argv[])
 
 			exit(EXIT_SUCCESS);
 
+		case 'R':
+			switch (gamemode_request_restart()) {
+				case 0: /* success */
+					LOG_MSG("gamemode restart succeeded\n");
+					exit(EXIT_SUCCESS);
+				case 1: /* already off */
+					LOG_ERROR("gamemode was already deactivated\n");
+					break;
+				case -1: /* error */
+					LOG_ERROR("gamemode_request_restart failed: %s\n", gamemode_error_string());
+					break;
+			}
+			exit(EXIT_FAILURE);
+
 		case 't': {
 			int status = game_mode_run_client_tests();
 			exit(status);

lib/client_impl.c

@@ -379,6 +379,12 @@ extern int real_gamemode_query_status(void)
 {
 	return gamemode_request("QueryStatus", 0);
 }
+//
+// Wrapper to call RestartGamemode
+extern int real_gamemode_request_restart(void)
+{
+	return gamemode_request("RestartGamemode", 0);
+}
 
 // Wrapper to call RegisterGameByPID
 extern int real_gamemode_request_start_for(pid_t pid)

lib/gamemode_client.h

@@ -103,6 +103,7 @@ typedef int (*api_call_pid_return_int)(pid_t);
 static api_call_return_int REAL_internal_gamemode_request_start = NULL;
 static api_call_return_int REAL_internal_gamemode_request_end = NULL;
 static api_call_return_int REAL_internal_gamemode_query_status = NULL;
+static api_call_return_int REAL_internal_gamemode_request_restart = NULL;
 static api_call_return_cstring REAL_internal_gamemode_error_string = NULL;
 static api_call_pid_return_int REAL_internal_gamemode_request_start_for = NULL;
 static api_call_pid_return_int REAL_internal_gamemode_request_end_for = NULL;
@@ -166,6 +167,10 @@ __attribute__((always_inline)) static inline int internal_load_libgamemode(void)
 		  (void **)&REAL_internal_gamemode_query_status,
 		  sizeof(REAL_internal_gamemode_query_status),
 		  false },
+		{ "real_gamemode_request_restart",
+		  (void **)&REAL_internal_gamemode_request_restart,
+		  sizeof(REAL_internal_gamemode_request_restart),
+		  false },
 		{ "real_gamemode_error_string",
 		  (void **)&REAL_internal_gamemode_error_string,
 		  sizeof(REAL_internal_gamemode_error_string),
@@ -319,6 +324,24 @@ __attribute__((always_inline)) static inline int gamemode_query_status(void)
 	return REAL_internal_gamemode_query_status();
 }
 
+/* Redirect to the real libgamemode */
+__attribute__((always_inline)) static inline int gamemode_request_restart(void)
+{
+	/* Need to load gamemode */
+	if (internal_load_libgamemode() < 0) {
+		return -1;
+	}
+
+	if (REAL_internal_gamemode_request_restart == NULL) {
+		snprintf(internal_gamemode_client_error_string,
+		         sizeof(internal_gamemode_client_error_string),
+		         "gamemode_request_restart missing (older host?)");
+		return -1;
+	}
+
+	return REAL_internal_gamemode_request_restart();
+}
+
 /* Redirect to the real libgamemode */
 __attribute__((always_inline)) static inline int gamemode_request_start_for(pid_t pid)
 {